topics: Fix translation issue with resolve topic notifications.
topics: Fix translation issue with resolve topic notifications.

In maybe_send_resolve_topic_notifications, since the calls to the
translation function `_()` are made outside of the `override_language`
block, the strings are not translated correctly.

This commit refactors the function to make sure that the translation
happens in the right block of code.

Fixes #19730.

rht/zulip,eeshangarg/zulip,eeshangarg/zulip,zulip/zulip,kou/zulip,andersk/zulip,rht/zulip,rht/zulip,eeshangarg/zulip,kou/zulip,kou/zulip,rht/zulip,zulip/zulip,zulip/zulip,eeshangarg/zulip,andersk/zulip,zulip/zulip,andersk/zulip,andersk/zulip,kou/zulip,zulip/zulip,rht/zulip,andersk/zulip,andersk/zulip,eeshangarg/zulip,kou/zulip,kou/zulip,rht/zulip,eeshangarg/zulip,rht/zulip,zulip/zulip,zulip/zulip,andersk/zulip,eeshangarg/zulip,kou/zulip